Currently discussed 4G cellular communication systems are designed on the basis of one basic frame to optimize their performances for users moving at a low speed. Though these systems are designed such that they can support users moving at a high speed of 350 km/h, their performance for high-speed users is considerably lower than those for low-speed users.
If these cellular communication systems are applied to a high-speed train without being modified, link quality between a network and the high-speed train decreases and sufficient link capacity is difficult to obtain because of high mobility of the high-speed train moving at 350 km/h.
Therefore, it is expected that performance deterioration of the cellular communication systems will become severe, thus remarkably degrading wireless data service for passengers if the velocity of the train exceeds 500 km/h. Furthermore, some of the capacity of a macro base station will be used by the high-speed train, and thus data communication of other users in the corresponding cell will be disturbed.
Wired communication instead of wireless communication may be used between the high-speed train and a network. For example, communication is performed between the high-speed train and the network through an AC signal using the tracks coming into contact with the high-speed train. However, this communication system has disadvantages that the tracks have small capacity and a larger number of links are difficult to generate because the number of tracks with which the high-speed train simultaneously comes into contact is limited to two.
In addition, PLC (Power Line Communication) using a power line may be used for communication of a moving body. However, this communication scheme has the same disadvantages as the communication scheme using the tracks and cannot be applied to trains having no power line.
As described above, it is difficult for the conventional frame structure, antenna arrangement and communication systems to secure link capacity and link quality for a high-speed moving body. However, no scheme for solving this problem has been studied or proposed.